The use of a nozzle is necessary in many pressurized systems that process liquids. Nozzles are especially useful, and indeed often necessary, in systems where high pressure, hot water is flashed into steam and then condensed to produce a more purified form of water. Sea water, gas and oil well production water, and other forms of water are processed in this manner to remove many of the contaminants and produce a more usable form of water.
Water purification systems employing evaporation or distillation principles often use a pump to pressurize the raw water, and a heater to heat the water to a high temperature. The heated water is then processed through a nozzle in an expansion chamber where the hot water flashes into steam. The portion of the heated water that does not flash into steam is removed, and the steam is carried to a condensation unit where it is condensed into the more purified form of water. In some production water processing systems, a nozzle is also used in a separator which separates the feed liquid into its constituent liquid, gas and solid components.
There are many sophisticated water purification systems that process large quantities of water through complicated processes to obtain pure water. Because of the complexity, the systems represent a substantial capital expenditure, and are often operated on a continuous basis in order to produce the desired amount of pure water. As such, it is imperative that the system and the components thereof perform reliably so that maintenance and repair is kept to a minimum. One component of such type of system that requires routine maintenance is the nozzle that transforms the high pressure, hot water into droplets that are flashed into steam in the expansion chamber. The dirtier the water that is processed, the more often the nozzle requires maintenance to remove deposits formed on the orifice surfaces, or to remove particulate matter that is too large to pass through the orifices. Often, filtration of the raw water is desirable to remove some of the particulate matter, however, the flash expansion process itself can form calcified deposits where they did not exist before in the stream of raw water. It can be appreciated that the system operation must be temporarily halted in order to replace the nozzle or otherwise remove the residue and deposits on the nozzle orifices. Because of the constant problem of nozzle failure, many water purification systems require regular monitoring to assure that the system is operating satisfactorily. In systems that process dirtier forms of water, and toxic water, the systems must be attended by an operator to provide continuous monitoring of system operation. This increases the overall operational cost of the system as well as the resulting product.
Evaporation nozzles heretofore known in the field can be constructed with no moving parts to increase the reliability and cost of the system. See for example, U.S. Pat. No. 3,930,960 by Taylor; U.S. Pat. No. 4,953,694 by Hayashi et al.; and U.S. Pat. No. 5,955,135 by Boucher et al. These types of nozzles simply pass the pressurized water through an opening or orifice to create a mist that flashes into steam when exposed to a reduced-pressure environment. As noted above, the orifices can become clogged or become less effective due to residue buildup on the orifice surfaces. Moreover, since these simple nozzles have no moving parts, they are not capable of responding to changes in the various parameters of the liquid being processed to change the operating conditions of the system. The nozzles of the prior art can also wear and increase in orifice size, and once the size of the nozzle orifice is changed, the characteristics of the system are also changed.
In the flash expansion systems of the type that heat the raw water to a high temperature, and pressurize the water with a pump, it is necessary to maintain the pressure of the heated water under control so that inadvertent flashing of the heated raw water does not prematurely occur in the system, other than at the expansion nozzle. Such an occurrence presents a corrosive condition to the system apparatus, thus severely shortening the life of the components. Thus, the pressure of the heated raw water must be monitored, and if changes are noted, such as a lowered pressure, then a control system must be responsive to such change and increase the speed of the pump or otherwise change other system parameters to restore the water pressure to the desired value. While this pressure control is certainly possible, and often necessary, the added components complicate the system and make it more costly. It would be desirable if the system could be at least partially controlled in this manner with the nozzle itself to control the orifice and regulate the pressure of the upstream raw, heated water to maintain the same within desired limits so that premature flashing of the hot water does not occur.
When employing nozzles of the type having a movable stem that moves a nozzle member with respect to a valve seat to form an orifice, one or more seals are often required to maintain a seal between the nozzle stem and a frame. Seals of such type must be able to withstand the high temperatures and pressures. Because of the severe environments in which such type of seals are used, the seals frequently deteriorate and fail. The replacement of seals in nozzle equipment requires that the equipment be taken off line, disassembled and repaired, which involves downtime of the system, costly repairs and lost production.
Nozzles can be spring operated to vary the size of the orifice as a function of the upstream liquid pressure. For example, if the upstream pressure of the liquid increases for some reason, such as a change in the density of the liquid being processed, then the spring in the nozzle further compresses so that the orifice opens to thereby lower the upstream pressure and restore it to the preset value. Such spring-operated nozzles are described in U.S. Pat. No. 7,963,459 by Sherry. As will be described in detail below, rather than using a spring to provide a counterforce to the pressure of the upstream liquid, a pneumatic or gas operated nozzle can be utilized as well.
From the foregoing, it can be seen that a need exists for an improved nozzle that is responsive to changes in various parameters of the liquid being processed to change the operating conditions of the system. Another need exits for a nozzle that is self cleaning and is effective to pass particulate matter that is otherwise large enough to clog the orifice. Another need exists for a nozzle structure that is designed to operate for long periods of time while processing dirty, particulate-laden liquids, and in harsh high temperature, high pressure environments. A much-needed advantage is a nozzle that operates in harsh environments without the need for high pressure seals. A further need exists for a nozzle that is operated by the pressure of the liquid processed therethrough, as well as a counterforce provided by a gas pressure. An additional need exists for a nozzle that controls the upstream liquid pressure by controlling the gas pressure that produces the counterforce.